The power system of electronic equipment needs to convert its input power to voltages acceptable to its load. The power system usually consists of many modules and components, and the architecture of the power system illustrates the interconnection of the said modules and main components. Usually, the power system is divided into two parts: power distribution from the input source to a circuit card, and power conversion on a circuit card. To reduce the voltage and current stresses of components on a circuit card, it is desirable to have one or more voltage regulators in the power distribution. The voltage regulators convert an input voltage from a power or voltage source to an output voltage within a voltage range that is suitable for the circuit cards of the electronics equipment. One or a plurality of voltage regulators can be used to deliver regulated power or voltage to one or a plurality of circuit cards in electronics equipment. In many systems, the input voltage from the power source to the voltage regulators and the output voltage from the voltage regulators to the loads are both direct current (DC). Accordingly, a significant part of the power system is a DC system. In many applications, it is desirable to design or configure the power system to operate at relatively high efficiency and provide relatively high power to electronics equipment. For example, the power system architectures may be optimized to reduce power consumption, provide stable and reliable operations, and/or reduce system space and thus system cost.